where \(J(\pi , \widehat{P})\)  can be estimated via the action-value function similar to standard offline MBRL algorithms [1]}, [2]}, [3]}.
Thus, when the dynamic model \(\widehat{P}\)  is fixed,
the main difficulty is to estimate the regularizer \(D_{\pi }(P^{*}, \widehat{P})\)  for the policy \(\pi \) .
